1. Field of the Invention
The present invention relates to a method and apparatus for diagnosing a link of a Fiber Channel Arbitrated Loop (FC-AL) system and, more particularly to, an FC-AL system link diagnosing method and apparatus for guessing a node highly possible to encounter a fault in a loop based on each node-specific fault history to, upon occurrence of a loop-related fault such as a link fault etc., disconnect the nodes from the loop in a descending order of the fault occurrence possibilities, thus detecting the node at which the fault occurred.
2. Description of the Related Art
As one system for interconnecting a computer and a storage apparatus is known a fiber channel, one connection form of which is also known an FC-AL. A variety of apparatuses connected to the fiber channel are called a node (node apparatus). The FC-AL employs such a link type (loop type) connection form that transmission units and reception units of FC ports make a round in a row over a plurality of nodes. Any system having such an FC-AL connection form, therefore, may be suspended in operation as a whole if a fault occurs at any of its nodes. To guard against this, each of the node is provided with a port bypass circuit in configuration so that a node where a fault occurred may be disconnected from the loop.
Japanese Patent Application Laid-Open No. Hei 11-353126 discloses a disk array connecting system which can easily identify a faulty apparatus to reduce time required in the identification processing. In this disk array connecting system, if a fault occurs, a loop of the system is disconnected once, so that then an initiator is connected with disk array apparatuses one by one sequentially for checking to thereby identify the apparatus where the fault occurred. When the faulty apparatus is thus identified, it is disconnected from the loop to then use another apparatus to restore the loop.
Japanese Patent Application Laid-Open No. 2000-174845 discloses a fiber-channel arbitration type loop faulty port detecting/excluding system and method for implementing unmanned early detection/exclusion of a port responsible for occurrence of a fault in an FC-AL. This faulty port detection/exclusion system and method utilizes one of the doubled loops to conduct bypass/enable control on a port where a fault occurred in order to exclude this port.
Japanese Patent Application Laid-Open No. 2000-215086 discloses a fault information collecting apparatus for, upon occurrence of a fault in a system connected to an FC-AL, automatically bypassing each port of an apparatus connected to a hub by linking a variety of types of monitors and then executing a testing/diagnosing program to collect information of the fault and manage the information as paired with log information.
Conventionally, if a link fault occurs in an FC-AL connected system, nodes are disconnected from the loop one by one sequentially while checking whether the link fault is recovered, thus searching for the node responsible for the fault. By this conventional method, however, the nodes must be checked sequentially until a port where a fault occurred is detected, so that this port cannot be detected early in some cases. The more nodes connected to the loop, the longer time it takes to detect a faulty port, during which ordinary input/output processing etc. cannot be performed.